In the question the option that tells us the weakness of the sampling technique is that Samples were taken from both dark and bright lunar areas instead of concentrating on one area
<h3>What is a sampling technique?</h3>
The sampling technique can be defined as the name of the technique that helps in the identification of the specific process by which the entities that would be used in a sample has been chosen.
This is the way that the subset of a population can be used to make generalizations about the entire population that is existent in the study.
Hence we can ay that In the question the option that tells us the weakness of the sampling technique is that Samples were taken from both dark and bright lunar areas instead of concentrating on one area
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More than 75 percent
Explanation:
Let us carefully analyze this problem:
The half life of the rubidium isotope = 50 billion years
The half-life of a radioactive isotope is the time it takes for it to decay to half of its original amount.
Every 50years, we know that a rubidium isotope would split into half.
Initially when the isotope was formed, we would only have the parent atoms there. There wont be any daughter;
ratio of parent to daughter = 100 : 0
When the isotope decays to half; we would have equal number of parent and daughter:
ratio of parent to daughter at half life = 50 : 50
The age of the earth is about 4.6billion years;
this is;
x 100 = 9.2% of the half-life of the rubidium isotope.
At this time, we should know that only 9.2 percent of the daughter would have been formed.
The remaining parent would be 100 - 9.2 = 90.8% would still be left undecayed.
The ratio of parent to daughter = 90.8 : 9.2
This is more than 75% of the parent
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Answer: Do it yourself
Find your scale. Maps have different scales e.g. for an explorers map 1:25,000.
Measure distance on map say in centimetres.
Use a ruler, string, or almost anything, pencil, fingers, a twig or I like a spare piece of paper.
Place against the scale for a direct reading.
Or calculate distance.
Say you measure 4 cm on the map. Then remember in this case 1:25,000.
so 4x1 or 4 = 4x25,000 = 100,000 cm real or actual distance.
In meters divide by 100 = 100,000/100 = 1,000 metres. (= 4cm on map).
or in kilometres divide again by 1,000 = 1,000/1,000 = 1 Kilometre. (= 4cm on map).
Also a tip just proved: 1:25,000 is the same as 4 cm = 1 Km or 1 cm = 1/4 Km real.
And best for walking a 1:50,000 scale map 2 cm = 1 Km or 1 cm = 1/2 Km real.
I believe the answer is D. Good luck!<span />
